Lorna Rothery spoke to Dr Cathy Price, Associate Professor in Pain Management and Vice President of the British Pain Society, about the difficulties in diagnosing, treating, and managing chronic pain
We know chronic pain can be an incredibly complex and multi-faceted condition. What are the key challenges in terms of diagnosis and treatment?
The International Classification of Diseases, specifically the section on pain, potentially contains at least 600 different pain diagnoses. However, most of these can be simplified and grouped into categories that align with the NICE (National Institute for Health and Care Excellence) guidance. Our improved understanding of pain mechanisms has allowed us to classify different types of pain into three primary categories. This is now incorporated into the curriculum for medical students and is also available as an E-Learning module through the faculty of pain medicine.
I’ll cover this classification briefly as it’s important to understand for the management of pain. The two main types of pain are acute, which is expected to resolve, and chronic, which is not expected to resolve. Moreover, there is cancer pain and non-cancer pain. Cancer pain is treated differently because it tends to be progressive and requires different treatments compared to acute and chronic non-cancer pain. This type of pain falls within the domain of palliative care, with pain teams and palliative care teams often working closely together. Another important aspect is the pain mechanism, referring to what happens to the nervous system when we experience pain. Long-term pain, in particular, can affect the nervous system. There are three main types of pain mechanisms: nociceptive, nociplastic, and neuropathic. Nociceptive pain is related to structural pathology, such as after surgery, fractures, or inflammatory conditions like rheumatoid arthritis. Nociception refers to the unpleasant sensation caused by the nervous system transmitting harmful information. Nociplastic pain is a newly proposed mechanism by the International Association for the Study of Pain. This type of pain arises from within the nervous system and includes conditions like fibromyalgia, non-specific chronic low back pain, and complex regional pain syndrome. It is covered by specific NICE guidance under the term chronic primary pain. Neuropathic pain is associated with nerve damage, so it’s important for doctors to identify the specific nerve that’s causing the pain. If they can’t pinpoint the nerve damage, then the pain may not be neuropathic. There are specific guidelines for diagnosing and treating neuropathic pain and how we think of pain because that has implications for prescribing and determining the appropriate interventions.
NICE has developed a series of pathways related to each type of pain. In terms of prescribing, we educate medical students and postgraduate doctors about different types of pain management approaches. For cancer pain, the World Health Organization (WHO) has established a pain ladder that involves gradually increasing the potency of medication from paracetamol to weak opioids to strong opioids. If there is nerve damage or underlying inflammation, anti-inflammatories or nerve pain medications are added as needed, following a progressive approach. However, the problem with this approach is that it has contributed to the opioid crisis in the United States, as it led to the overprescription and misuse of opioids. Consequently, we have identified two other pain management approaches: the acute pain ladder, which reverses the WHO ladder and begins with an assessment of pain severity before matching the strength of opioids, with the goal of gradually decreasing opioid use, and the chronic pain ladder, which does not involve progression but instead focuses on understanding the specific type of pain being dealt with. For nerve damage pain, we would follow NICE guidance on prescribing different types of neuropathic agents. In cases of inflammatory pain, short bursts of anti- inflammatories may suffice. However, for nociplastic pain (otherwise called chronic primary pain), antidepressants, and specific types of antidepressants, are recommended, and the dosage is adjusted according to the patient’s needs. This is how we approach and classify pain in a more scientific manner and tailor treatments accordingly.
Do patients find it frustrating to suffer from an ‘invisible condition’?
Depression is often closely linked to a significant number of chronic pain diagnoses. The frustration and difficulty of being unable to do things can lead to feeling useless, which in turn can cause a person to feel very low. Conversely, existing low mood or anxiety can exacerbate the ability to manage pain. While we don’t fully understand the connections between anxiety, low mood, and pain, we do know that they are definitely connected. While some people may not experience a strong relationship between these factors, for others, there is a clear connection.
A comprehensive assessment is needed to address these issues. Beyond the physical mechanisms, it’s important to consider the psychosocial factors at play. These factors may not be immediately obvious, but there are specific things to look for, and once identified, appropriate interventions can be matched. Psychological treatments for pain can be challenging to deliver and may not be accessible to everyone. Though outcomes are relatively positive compared to other chronic pain interventions, there are still limitations.
Accessing the right treatment when dealing with depression and pain or anxiety and pain together can be quite challenging. Nevertheless, it’s important to recognize these challenges and support individuals in managing them.
Although treatments acknowledge the multifaceted, biopsychosocial nature of pain, has medical practice kept pace with the science? Are there any notable developments or current issues in pain research that you think our readers should be more aware of?
One of the major challenges lies in translating research findings from the lab to clinical practice. In the UK, initiatives such as the Advanced Pain Discovery Platforms have been set up to consolidate information from various sources, including trials and population data, to identify the most promising research directions. Advancements in AI and other technologies have made it possible to link and analyse this information more effectively.
In terms of treatment, we are still facing challenges in translating research into practice. I have conducted research on the cost-effectiveness of different interventional pain procedures, including nerve root blocks. Our findings have indicated that precise nerve root blocks can be more advantageous than surgery in some cases. However, the effectiveness of less precise blocks, such as general epidurals, is limited.
Advances in interventional techniques and devices have been made, but further research, particularly independent of industry funding, is needed to clarify the efficacy and placement of these devices. Imaging technologies such as fMRI and PET scans have significantly contributed to our understanding of the nervous system and the brain, leading to the development of improved psychological techniques.
Although there have been advancements in communicating the science of pain, there is still a need to improve access to effective interventions. Understanding cultural and social differences is crucial in developing interventions that are effective for diverse populations. Additionally, efforts to reach underserved populations, such as those in areas of social deprivation, are underway in places like Bradford, Liverpool, and Hackney.
It is crucial to collaborate with patients and individuals who have experienced pain when developing interventions. I’ve found this approach to be highly beneficial in our research. For instance, when we worked on return-to-work interventions, it was the input from individuals with lived experience that truly improved these interventions. Instead of just listening to them, we need to actively work with them. The same principle applies to communities that we are currently not effectively reaching. We must collaborate with these communities to design interventions that are tailored to their needs rather than developing interventions and then testing them out. Despite collaboration being common, I believe we should go further and faster.
